<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>监听子组件事件</title>
    <style>
        #app{
            width: 600px;
            margin: 40px auto;
            text-align: center;
        }
    </style>
    <script src='/js/vue.js'></script>
</head>
<body>
    <div id='app'>
        <h2>当前计数器的值为: {{num}}</h2>
        <counter v-on:counter-add="num++"></counter>
    </div>
    
    <script>
        Vue.component('counter', {
            template: '<button @click="add">计数器</button>',
            methods: {
                add: function(){
                    this.$emit('counter-add')
                }
            }
        })
        let app = new Vue({
         el: '#app',
         data: {
          num: 0
         },
         methods: {
            handleAdd: function(){
                this.num++
            }
        }
        });
    </script>
</body>
</html>